The present invention relates to a process for producing a granular, fire-resistant (or fire-proof) material, more particularly, such material which contains ceramic fibers, a refractory such as clay, a bonding agent, and, optionally, another refractory material and/or a plasticizer.
The present invention also relates to the granular, fire-resistant material produced by this process, and the use of such material in applications where fire-resistance is desired.
The art is aware of heat-insulating, ceramic fiber bodies, made of fire-resistant or fire-proof fibers and organic or inorganic bonding agents, having low stability and high compressibility, or having increased stability, density and nondeformability. For example, German Patent Specification DE-AS 12 74 490 describes a combustion chamber for furnaces, constructed by shaping a composition containing fibers and bonding agents, in such a manner that the concentration of bonding agent varies across the cross-section of the furnace wall. This reference mentions different types of clay, alkali-silicates, aluminum phosphates and colloidal siliceous earth, in an amount of 5 to 35% (optimum of 10%) by weight, as suitable bonding agents. However, such fiber bodies are not sufficiently suited for application of high stress, since one wall surface is dense and hard, and the other, opposite, wall surface is soft and flexible.
Another German Patent Specification, DE-AS 27 32 387, discloses a process wherein a mineral fiber-board, which has been hardened in advance with an organic synthetic bonding agent, is soaked in an aqueous solution of a bonding clay and subsequently hardened through tempering.
Furthermore, DE-AS 26 18 813 discloses fiber spraying-compositions which contain, in addition to a large amount of inorganic fibers, a small amount of bonding agent and/or inorganic components as well as an additional chemical bonding agent. These fiber spraying-compositions also contain 5 to 20% by weight of an oil, to avoid dust formation. Instructions for use of these fiber spraying-compositions expressly indicate that the inorganic fibers, such as rock wool, have to be used in a loosened condition.